Improvement in slide-valves for steam-engines



IsAAO v. HOLMES, OF NEW YORK, N. Y.

IMPRVEMENTIN SLIDE-VALVES FOR` STEAM-ENGINES.

Specicai ion forming part of Letters Patent No. 12,E9ll, dated April 5, 1864.

. To all whom it may concern:

Be it known that I, IsAAc V. HOLMES, of the city, county, and State of New York, have invented a new and useful Improvement in the SlideValves of Steam-Engines and I do hereby declare that the following is a full, clear, and exact description of the same, reference being had to the accompanying drawings, forming part lof this specification, in which- Figure l is a longitudinal section of a slidevalve and riding cut-off valves in a plane perpendicular to its face. of the valve. Fig. 3 is a section of the same, parallel with its face in the plane indicated by by the line x in Fig. l. Fig. el is a plan of the cut-oii' valves.

Similar letters of reference indicate correspending parts in the several figures.

In slide-valve steamengines it is desirable, more especially in those of large size, to obtain a full openin g of the port with the smallest practicable movement of the valve. To obtain this result it has been common to make the valve double-ported, butin making the valve double-ported, both for steam and exhaust, a difficulty has arisen-viz., the want of an eective mode of applying a cut-off, the arrangement of the port-s having rendered it impracticable to apply a cut-off valve or valves riding directly on the back of the main valve.

This invention consists in the combination, with a slide-valve which is doubleported, both for steam and exhaust, of a cut-off valve or valves riding directly on the back thereof.

It also consists in a certain arrangement of the ports in such double-ported valve whereby the application of the cut-od' valve or valves riding directly upon its back is made practicable.

To enable others skilled in the art to make and apply my invention, I will proceed to de- Fig. 2 is a back viewface of the valve, communicating with the cavity g, which extends as nearly as possible the entire length and width of the valve. The ports c e operate in combination with the two ports c c of the valve-seat, and the port j' operates in combination with thc two ports d d', and also with the main exhaust-port h in the seat.

The ports a a', c e', and fare severally made of a length equal, or as nearly so as practicable, to the full width of the valve, but in order to provide for a free communication between the two exhaust-ports c o', and the center exhaust-port,f, and main exhaustport h, the twoy ports b b are made much shortersay, only of about one-half that lengththereby making passages i i (see Fig. 3) at each end of the said ports, by which the steam exhausted through e e nds it way to f and h. It is by this construction of the valve with short ports b b and passages it" that I am enabled to bring the four steam-ports all into the back of the valve, thereby permitting the application of the riding eut-off valves D D directly upon the back of the doubleported valve, and reducing the capacity of the space between the cut-ofi' valve and cylinder in the greatest practical degree.

Instead ofthe two ports I) b', arranged in the middle of the valve with a passage between them, there may be four ports of half the lengthviz., two in place of b and two in place of b/ arranged close to the sides of the valve, with a passage between them for the exhauststeam. This would be equivalent to the arrangement represented in the drawings.

The cutol' valves l) D are made each of a size and form shown in Fig. 4 to cover one of the longer steam-ports c a and the corresponding shorter one b or bf, and with a port, j, ar-

ranged to uncover and cover the port b or b', as the outer edge, 7e, of the valves uncovers and covers the corresponding port a or c. The said cut-off valves are represented in Fig. l as attached to the same rod E. They may be adjusted and operated in the same manner as the riding cutoff valves applied on the back of a single-ported slide-valve.

The two cut-off valves may be combined so as to form literally but one valve, or they may be each divided into two, making one for each port; but the'construction Ihave represented is the best, as it permits all the necessary adjustnzent without making the parts more nuhausted through two of the exhaust-ports e e merous than is desirable. may pass the inner stea1nports,b b', on its Way What I claim as my invention, and desire to to th emain exhaust-port, substantially as heresecure by Letters Patent, isin described, and all the steam-ports are 1. The combination, with a slide-valve which brought vinto the back of the valve, so that la isl doub1eported, both for steam and exhaust7 cut-off valve or Valves may be applied to ride of a cut-oit' Valve or Valves riding directly on directly thereon7 substantially as herein specithe back thereof, substantially as herein specitied.

lied. ISAAC V. HOLMES.

2. The construction and arrangement ot' the Witnesses: several ports of a double-ported valve, sub- M. M. LIVINGSTON,

stantially as described, whereby the steam eX- J. W. COOMBS. 

